Something to think about................... What if the EGR cooler worked just opposite of the way it was designed to work ? It was designed to remove heat by using the coolant in the truck. I feel that with the amount of water that is being circulated and the amount of exhaust gas that is being recirculated that the EGR cooler is boiling the water. We all know that when you boil water the calculation is 1500 to 1 This would create more pressure on the motor block then the boost off of the turbine does. Think about it. Just doing a little figureing it might be seing around 250-300 lbs of pressure. as the water boils. Now remember this is just for an instant. Just my 2 cents worth

 

This is good stuff Ira...we need to think out of the box on this one.....I still believe we are missing the boat on this....IMO...just a feeling I got.

...like have we thought about the water speed… at temp, and how fast this motor will climb in RPM...could it be cavitations… the impeller a bit dry....when it catches up shoots a lot of water through it....could we have a hot spot on the back right cylinder head that is causing a bubble

….if we were blowing head gaskets we would see more sever damage on the ones that have been doing it for a while..leaking head gaskets have a way of making a small problem big in short time

 

Tim, the way I try to approach problems like this is how I worked on servers and networks. I go from the standpoint of what has changed recently. That being said, what really has changed from the mechanical standpoint between the 7.3 and the 6.0 when it comes to cooling?

If we follow this than the 1st thing I come up with is the stupid EGR. Would you agree that a diesel engine is a diesel engine? What I mean is they all are basically the same in how they operate, so what is the big difference that is now causing issues? I wonder if PSD could add some wisdom as to how the coolant lines run and by taking a look at that where the possible weak points are. I am under the impression that they run under the plenum or manifold as it were since they had to tear down the top of my motor to replace them. If that is the case could vibration be an issue, or, like was surmised in a post above what if the water that is supposed to be cooling is actually boiling as it runs through these lines? It would be interesting to add dye to the coolant on a motor that is loosing it and then tear down the top half to see where it went or be able to take a temp reading from the lines themselves while the motor is working hard. I have a feeling this is going to be one of those Duh! moments when we finally figure it out.

 

Your methodology to problem solving is spot on.....I agree and believe the EGR is the root of many problems, which also (IMO) has been difficult for some dealerships it diagnoses…..strange but true. I wonder where Matt has been.

 

I hope someone gets a handle on this. My truck is going back in the shop for the forth time to see if they can fix it.They have replaced the coolant bottle then the head gaskets and then the heads and now they are going after the EGR to see if that might cure the problem. As soon as they get the EGR cooler out I am going to take some measurementa and see if what I am talking about might be true. This piece of equipment was designed for a specific amount of water and exhaust gas heat thansfer. Once they are outside those boundries I feel we need to see what is happening. All you refinery workers out there you know the EGR cooler in nothing more than an heat exchanger . So when the amount of product you push through it becomes hotter the water leaving the exchanger becomes hotter so you have one of two options increase the amount of water through the cooler or increase the size of the cooler to give it more contact time. OK thats my 4 cents worht for today.

 

It would be interesting to see if there was a way to shut off the coolant flowing through those lines and isolate the EGR and then run the truck to see what happens. The more I think about this the more my "gut" tells me this new EGR comes with a lot of unintended consequences!

Bark, that is a great idea, wish I would have thought of that when mine was torn apart, please keep us informed....

PSD, if you are listening, would it be possible for you to get the measurements from a new set of lines? I am sure (hoping) that our current moderator math wiz would be able to figure out flow rates and heat exchange with that calculator behind his ear..

 

This is lending credence to my theory it is not he head gaskets…something I have believed since day one…just cannot figure what we are missing.

 

You guys wondering where I'm at?

Heh....ironically enough, I have spent all weekend tearing the top end of my engine out...for what you ask?

To replace my head gaskets...

Tim, as you and I have previously discussed...my issue WAS my head gaskets.

The cylinder pressure of my stack tune was going right through them. I reinstalled another tune (of very unlike parameters) only to have the coolant leak go away complely. Sunday morning, upon reloading my stack tune (Edge and SCT) the driver's side completely cut loose with me. Lost MASSIVE amounts of coolant and oil- towed her home (rather than drive it like last time)...

The engine is fine now, after 13 hours of work to replace both head gaskets. The driver's side turned out to be the bad one; from appearance it seems to have failed on the back two cyliders, right between the MLS layers, both on the inside and outside. Thankfully, most of it ended up on the pavement rather than getting digested. Engine runs just fine now, and seems to be marginally more powerful. I get the feeling that the gasket had been leaking internally for quite some time. The new head bolts are extremely overtorqued (about 60ft/lbs) and the truck now runs the stack tune, with water and propane, with no coolant loss/boilover whatsoever.

On alot of trucks, however, the EGR system is of utmost concern. Even Ford and International is aware of this. There are a couple other people who can post there experiences with this.

I think SOME of these trucks may have head gasket issues leading to the coolant loss. However, I certainly agree with Tim that something else lies under the covers here.

As for an EGR bypass, it shouldn't be terrifically difficult to do. Two blockoff plates and a coolant bypass tube will be all that is needed, but fabrication of the tube could be interesting...I'll see what I can work up in respects to it tomorrow. TOO much stuff to do- college apps, fixing truck, work...trying to type at 2:12 in the morning, ect.

Goodnight.

PS- guys with blowing coolant issues- do me a favor- go check your Degas bottle. Let me know if there are black flakes stuck in the bottom- report back as soon as you can.

 

I need a little info about when the computer determines when the motor needs to recirculate exhaust gas. Can someone please let me know how it is determined. Seems there is some speculation about overboosting and this causing the engine to leak coolant. I am working on the calcs on the EGR cooler and while doing this my brain has asked me a ? How does it recirculate the exhaust gas ? If I am running 20 lbs of boost and the computer tells the engine it is time to recirculate exhaust gas then my exhaust pressure is going to have to be higher then the boost pressure so the vanes in the turbo close causing the exhaust backpressure to build and the truck possibly overboosting. Think about it Thats my six cents worth for today.

 

Ira Matt needs to jump in on this one...if we can get him out of bed before 12 noon

 

Probably too worn out installing his monsta motor.....

 

I don't have guages but do have an AutoXray scan tool. Back when my truck was having problems idling rough and the cycling engine noise of quiet to normal at cruising speeds..... Ultimately the problem was the EBP, exhaust back pressure, sensor. What the scan tool showed was EGR (flow) error of 99.9% during these problem periods, even at idle.

I think what you are saying about the back pressure being controlled by the EBP is correct; and I also believe that the PCM is using some other strategy to control the EGR position (least ways with the flash mid year that eliminated my EGR quiet idle strategy).

If you read the documents on motorcraftservice.com for the emissions control.... The PCM can determine EGR flow error based on the mass air flow sensor. It knows what the total air required is based on an internal table; if it isn't coming from the intake (MAF) then the rest can be assumed to be EGR flow. During the problem moments with my engine I could actually see low MAF during the high EGR flow error relative to times when the engine was not having the problem. (My problem moments were intermittent but progressively became more frequent).

I might add that during these periods of excessive EGR flow the exhaust overwelmingly "STINKS" to the excess!!!

I don't believe that the EGR position was being controlled based on calculated EGR flow but probably some table; hence when the EBP was bad it was creating too much back pressure and therefore too much EGR flow. Probably too much boost too!

Unfortunately the AutoXray 6000 scan tool does not provide a multitude of data and would indicate DTC count but not display any! So I don't know if I had overboost or not.

It doesn't display EBP. It has a field for EGR command but always displays zero. When displaying MAP values which are absolute and in inches mercury (IIRC) you have to subtract BARO and basically divide by 2 to get PSI.

My Baro is around 29 to 30; the MAP value at idle is the same as BARO (IIRC) and at WOT would climb to 99 then indicate up to 07 or 09. I believe the scan tool had a problem of only displaying two digits and the actual value was 107-109. My quick and dirty calculation was (109-30)/2 = 39 lbs. boost; high. The actual value to divide by is really closer to 1.9 something IIRC. Only thing is this value still is rolling over to similiar values w/o the EGR problem. I need to break down and buy the gauges...

I exchanged a few E-MAILs with AutoXray and I'm not holding my breath for them to correct anything. There are other problems with this scan tool with respect to the 6.0 PSD.

It does display coolant temperature though. I was very surprised how much my coolant temp rose when the gauge on the dash wasn't moving at all while pulling the travel trailer early summer w/ outside temp of 80 degrees. IIRC the coolant went up to 210; probably the EGR cooler! I don't even think I was running the A/C and the terrain was basically flat at 70 MPH.

I had the EGR unplugged for 5000 miles during one oil change interval (wanted to see if oil looked any better; couldn't tell any difference). During this period and pulling the TT to Branson I was watching the coolant temperature and it never got above 200. This was with higher outside temperatures, A/C running, and some good hills; some ran at a legal 75 MPH on the turnpike.

Bob

 

This is news to all of us and something we now must take into account when trying to figure this out.

 

Could you imagine what the coolant temp would be if you were loaded with 17000 lbs and the outside temp was 98 dg like it is here in south texas. The tuning on the factory gauge is hardly relevant to what the coolant temp is actually doing. The factory does this so people don`t worry about the guage moving a little so it might take 5-7 dg for it to move any.

 

I Lost about 1 1/2 gallons of coolant in one week. It seems to be coming from head gasket at rear passenger side. Had it to dealer and they say they can't find the leak and will not do anything with it until they see it.